Stretch student with English afterwards (8)
I believe the answer is:
lengthen
'stretch' is the definition.
(thesaurus)
'student with english afterwards' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'with' says to put letters next to each other.
'english' becomes 'eng'.
'afterwards' becomes 'then' (I've seen this before).
'l'+'eng'+'then'='LENGTHEN'
(Other definitions for lengthen that I've seen before include "Protract" , "Elongate" , "Extend or draw out" , "Prolong" , "Make or become longer" .)